Method for restricting midpoint potential drifting of three-level inverter in direct drive wind power system

• Main Authors: XIA CHANGLIANG, SHI TINGNA, GU XIN
• Format: Patent
• Language: Chinese; English
• Published: 30.06.2010
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERATION; REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGYGENERATION, TRANSMISSION OR DISTRIBUTION; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE

The invention belongs to the control field of energy conversion devices of high capacity direct drive permanent magnet synchronous wind power systems, relating to a method for restricting the midpoint potential drifting of a three-level inverter. The method comprises the following steps of: determining the work mode of a three-level boost converter, calculating a critical inductance value, and determining a boosting inductance value; collecting a generator rotate speed signal of a direct drive wind power system and two capacitor voltage signals at direct current sides of the three-level boost converter; carrying out PI regulation according to a difference value between an actual rotate speed and a reference rotate speed by a microcontroller, and then outputting a reference value d* of the boosting ratio of the three-level boost converter; calculating a difference value between the two capacitor voltage signals at the direct current sides, carrying out PI regulation of the other path on a difference value betw